BackedBy is a protocol designed to enable monthly subscriptions between creators and their supporters, but it can be extended for any recurring monthly payment purpose. The smart contracts powering this protocol are non-upgradable, extensible, and composable. You can find them at the following addresses:
subfactory https://polygonscan.com/address/0x5D2A904E7374cc3FaA5658Ecd462e370aA4637a6
tiers https://polygonscan.com/address/0xfFec1c5B14808D56a894916A52da300d8eE77941
posts https://polygonscan.com/address/0x35bb26163E8Ec8542863D270fd92927F562Af1C6
profiles https://polygonscan.com/address/0x096741579bAC68b4044Bbb4966D390E51081c7dC
gas oracle https://polygonscan.com/address/0xce73af240eB43bBbf16223D206400F0602fb1b70
USDC https://polygonscan.com/address/0x654B5903544E7c1Af996b98cC38DA1A37684a1Ae
USDT https://polygonscan.com/address/0x495eB78a0B48077e0A097AF07194636FC85dAdE4
DAI https://polygonscan.com/address/0x628AE6F0F30F1Cf9DFB287b03D011cF855818c47
The contracts have been audited by Certik, a leading authority in blockchain security audits and the results can be found at https://www.certik.com/projects/backedby.
The UX layer at backed.by is developed separately and provides the best possible experience for the monthly subscription contract listed above. Including encryption via the Lit Protocol, and Web2 features like user administration, profile management, billing, and notifications. However, the contracts are public and any platform or integration can be built around them.